1. Field of the Invention
The field of the invention relates generally to superconducting transmission delay lines which may be used to keep a constant electrical delay length or maintain a constant impedance. More particularly, the invention relates to a system and method permitting users to adjust a variable superconducting transmission line incorporating feedback loops to achieve a precise electrical delay length or an impedance value.
2. Related Art
A typical delay line used at RF and microwave frequencies is a trombone line with a mechanically variable slide. As part of the line slides along with respect to the other line (the fixed line), the delay line length increases. Ideally, the impedance will stay constant and the electrical length will be fixed. In reality, however, there is always some small amount of impedance mismatch. The electrical length is seldom constant due to mechanical stresses and temperature variations. Lastly, the trombone delay line is a large bulky device which requires machining and is expensive to manufacture.
As can be seen from E. Track et al.'s paper titled, "Modulation of the Penetration of Nb and NbN Films by Quasiparticle Detection", (I.E.E.E. Transactions on Magnetics, Vol. 25, 1989, pg. 1096), superconductive traces can give rise to a controllable inductor.